Pick Tool with a Removable Shank

ABSTRACT

Pick tool assemblies for use with formation degradation machines, such as road milling, mining, trenching or drilling machines, may be disposed on rotatable drums, wheels, continuous chains, drill bits or the like and brought into engagement with such formations as rock, asphalt, coal or concrete to break up or otherwise degrade the formations. Such pick tool assemblies may comprise a shank comprising a forward end and a rearward end wherein the rearward end may be formed for retention in a bore of a block attached to a driving mechanism and the forward end may comprise a body detachably and nonrotatably fastened thereto. Further, an impact tip may be bonded opposite the rearward end.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Pat. App. No. 61/678,384 filed on Aug. 1, 2012, which is incorporated herein by reference for all that it contains.

BACKGROUND OF THE INVENTION

The present invention relates generally to formation degradation machines such as the type used in road milling, mining, trenching or drilling. More specifically, the present invention relates to pick tools used by formation degradation machines for engaging and degrading a formation. Pick tools may be disposed on rotatable drums, wheels, continuous chains, or drill bits and brought into engagement with such formations as rock, asphalt, coal or concrete to break up or otherwise degrade the formations.

While degrading a formation, pick tools may be subjected to severe abrasion and thermal wear. However, different portions of pick tools may wear at different rates. For example, exposed portions of a pick tool may experience rapid wear while shielded portions may experience little to no wear. Thus, it may be desirable to replace those portions experiencing the most wear relatively frequently while retaining those portions in place that receive less wear.

An example of a pick tool is found in U.S. Patent No. 7,401,863 to Hall et al., herein incorporated for all that it contains, which discloses a pick comprising a shank attached to a base of a steel body, a cemented metal carbide core press fit into the steel body opposite the shank, and an impact tip bonded to a first end of the core opposite the shank. In this example, wear on any portion of the pick tool may require replacement of the entire tool, thus wasting unworn material.

Another example of a pick tool is found in U.S. Pat. No. 4,804,231 to Buljan et al., herein incorporated for all that it contains, which discloses a cutter bit holder that has a replaceable cutter tip which can be replaced in the field when the cutter tip is worn by unscrewing a flange from the shank of the holder and replacing the worn cutter tip with a new one. However, Buljan et al. relies on a threaded connection that may undesirably rotate during use.

Thus, while known pick tools may have proven acceptable for their intended applications, there remains a need for improvement in the pertinent art.

BRIEF SUMMARY OF THE INVENTION

A pick tool assembly may comprise a shank comprising a forward end and a rearward end wherein the rearward end may be formed for retention in a bore of a block attached to a driving mechanism and the forward end may comprise a body detachably and nonrotatably fastened thereto. Further, an impact tip may be bonded opposite the rearward end.

In some embodiments of the pick tool assembly, the impact tip may be bonded to the forward end. In such embodiments, the forward end may be disposed within a cavity passing completely through the body.

In other embodiments, the impact tip may be bonded to the body such as by being brazed in a recess of the body or some other means known in the art. In such embodiments, the forward end may be disposed within a socket within the body. To aid in transferring forces between the body and the shank, the body may comprise a radial flange disposed adjacent the socket that may interact with an outer shelf disposed around an exterior of the forward end.

The forward end may be press fit within the socket of the body. To aid in the press fit, the forward end in various embodiments may be hollow, slotted, tapered or combinations thereof. In some embodiments, the forward end may comprise a compliant ring disposed thereon or a pin insert to aid in retention within the socket.

The driving mechanism may comprise a drum, wheel, chain, or bit with a block attached thereto. The shank of the pick tool assembly may be nonrotatably retained in the bore of the block. Also, the body may comprise at least one detachment groove disposed adjacent the forward end to aid in detaching the body from the forward end and the forward end may comprise at least one detachment groove disposed to aid in detaching the shank from the block.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 discloses an orthogonal view of an embodiment of a road milling machine comprising a rotatable drum.

FIG. 2 discloses a cut-away orthogonal view of the rotatable drum of the embodiment shown in FIG. 1.

FIGS. 3 a, 3 b and 3 c respectively disclose exploded orthogonal, unexploded orthogonal and longitudinal section views of an embodiment of a pick tool assembly comprising a slotted shank.

FIG. 4 discloses an orthogonal view of another embodiment of a pick tool assembly comprising a flanged shank.

FIG. 5 discloses a longitudinal section view of another embodiment of a pick tool assembly comprising a hollow slotted shank.

FIG. 6 discloses a longitudinal section view of another embodiment of a pick tool assembly comprising a compliant ring.

FIGS. 7 a and 7 b respectively disclose orthogonal and longitudinal section views of another embodiment of a pick tool assembly comprising a pin insert.

FIG. 8 discloses a longitudinal section view of another embodiment of a pick tool assembly also comprising a pin insert.

FIGS. 9 a and 9 b disclose longitudinal section views of other embodiments of pick tool assemblies each comprising a body comprising a cavity fastened to a shank.

FIG. 10 discloses a perspective view of an embodiment of a trenching machine comprising a rotatable wheel.

FIG. 11 discloses an orthogonal view of an embodiment of a trenching machine comprising a continuous chain.

FIG. 12 discloses an orthogonal view of an embodiment of a drill bit.

DETAILED DESCRIPTION OF DRAWINGS

Referring now to the figures, FIG. 1 discloses an embodiment of a formation degradation machine in the form of a road milling machine 100. The road milling machine 100 may travel over a degradable surface 101 that may be a man-made roadway such as those comprising pavement, concrete, or asphalt or it may be a naturally occurring earthen formation. A rotatable drum 102 may be secured to an underside of the road milling machine 100.

FIG. 2 discloses the rotatable drum 102 of FIG. 1 comprising a plurality of pick tools 220 disposed around an exterior thereof. The rotatable drum 102 may be driven such that the pick tools 220 engage and degrade the degradable surface 101.

FIG. 3 a discloses an embodiment of a pick tool assembly 301. In the embodiment shown, the pick tool assembly 301 comprises a shank 302 comprising a forward end 303 and a rearward end 304. The rearward end 304 of the shank 302 may be adapted for retention in a bore of a block attached to a driving mechanism such as a rotatable drum, wheel, continuous chain, or drill bit. A trailing end 305 of a body 306 may be detachably fastened to the forward end 303 of the shank 302. The body 306 is unable to rotate with respect to the shank 302. The body 306 comprises an impact tip 307 permanently bonded on a leading end 308 of the body 306 opposing the shank 302.

The body 306 and impact tip 307 may be the most quickly worn parts in the pick tool assembly 301. Having a shank 302 that is detachably fastened to the body 306 may be beneficial because it may allow for the timely replacement of the body 306 and impact tip 307. The shank 302 of the pick tool assembly 301 may last longer than the body 306 and the impact tip 307 because the shank 302 may be disposed in the bore of a block and shielded by the body 306. The shank 302 may still be functional when the body 306 and impact tip 307 have lost their usefulness. By making the shank 302 removable, the overall tool life of the pick tool assembly 301 may be increased because the shank 302 may be reused several times while the body 306 and the impact tip 307 are detached and replaced. Additionally, the proposed invention may be beneficial because the body 306 may undergo different treatments or other finishing operations than the shank 302. This may allow for more specialized customization of the properties of the shank 302 and the body 306 and improved performance and wear resistance overall. For example, the shank 302 may be made from inexpensive steel while the body 306 may be made from stronger, heat-treated steel. The body 306 may also be hard-faced with more wear-resistant materials to improve its life.

FIG. 3 b discloses the pick tool assembly 301 of FIG. 3 a. The impact tip 307 may comprise a superhard material 309, such as polycrystalline diamond, sintered to a carbide substrate 310 brazed to a carbide bolster 311. The impact tip 307 may be the first portion of the pick tool assembly 301 to contact a surface being degraded by the pick tool assembly 301 and thus may experience extremely abrasive conditions during use. The body 306 may be the second portion of the pick tool assembly 301 to contact a surface being degraded and thus may also experience significant abrasive conditions. While the impact tip 307 may experience more abrasive conditions than the body 306, the superior toughness of the superhard material 309 as compared to the carbide bolster 311 and of the carbide bolster 311 as compared to the body 306 may cause more substantial wear on portions of the pick tool assembly 301 further from the superhard material 309. The shank 302 may be shielded from significant wear by the body 306.

The body 306 may further comprise one or more detachment grooves 314 disposed on a flange of the trailing end 305 of the body 302. The detachment grooves 314 may aid in removal of the body 306 from the shank 302 by allowing a pick removal tool to be inserted between the body 306 and a block.

FIG. 3 c discloses the pick tool assembly 301 of FIGS. 3 a and 3 b. The leading end 308 of the body 306 may comprise a recess 315 therein in which the impact tip 307 may be disposed. In the embodiment shown, the impact tip 307 is brazed to the body 306, however, it may also be attached by other methods known in the art such as press-fitting.

The rearward end 305 of the body 306 may comprise a socket 316 in which the forward end 303 of the shank 302 may be disposed. The forward end 303 may be press fit within the socket 316. The forward end 303 may also comprise various features that may aid in the press fit. In the embodiment shown, the forward end 303 comprises a slot 317 that may aid in the press fit by causing it to be more pliant. The forward end 303 may also comprise a slight taper as shown to aid in the press fit.

FIG. 4 discloses another embodiment of a pick tool assembly 401. The pick tool assembly 401 of this embodiment may comprise a body 406 comprising a radial flange 425 disposed on a trailing end 405 thereof and a shank 402 comprising an outer shelf 418 disposed around an exterior of a forward end (hidden) thereof. Contact between the radial flange 425 and the outer shelf 418 may aid in transferring forces experienced by the body 406 to the shank 402.

A detachment groove 424 may be disposed on the outer shelf 418. The detachment groove 424 may aid in removal of the shank 402 from a block by allowing a pick removal tool to be inserted between the outer shelf 418 and the block.

FIG. 5 discloses yet another embodiment of a pick tool assembly 501 with a forward end 503 of a shank 502 press fit within a socket 516 of a body 506. In the embodiment shown, the forward end 503 comprises both a slot 517 and a hollow section 519 that may aid in the press fit by causing the forward end 503 to be more pliant.

FIG. 6 discloses an additional embodiment of a pick tool assembly 601. In this embodiment, a compliant ring 613 is disposed around a forward end 603 of a shank 602 that may aid in press fitting the forward end 603 into a socket 616 of a body 606. The compliant ring 613 may compress when the shank 602 is inserted into the socket 616 and thereby assist in retaining the body 606 on the shank 602.

FIG. 7 a discloses a further embodiment of a pick tool assembly 701 comprising one or more cylindrical pin inserts 720 which may assist in retaining a body 706 on a shank 702. While in place, the cylindrical pin inserts 720 may prevent the body 706 from detaching from or rotating with respect to the shank 702. The cylindrical pin inserts 720 may be slid out of place when the body 706 is to be removed from the shank 702.

FIG. 7 b discloses the pick tool assembly 701 of FIG. 7 a. Holes may be drilled through portions of both the shank 702 and the body 706 allowing for the cylindrical pin inserts 720 to be inserted therein.

FIG. 8 discloses another embodiment of a pick tool assembly 801. In this embodiment, one or more square pin inserts 821 may assist in retaining a body 806 on a shank 802. It is believed that square pin inserts 821 may be easier to manufacture and install than other geometries of pin inserts and may thereby be desirable.

FIGS. 9 a and 9 b disclose additional embodiments of pick tool assemblies 901 a and 901 b respectively. The pick tool assemblies 901 a and 901 b each comprise an impact tip 907 a, 907 b bonded to a forward end 903 a, 903 b of a shank 902 a, 902 b. In the embodiment shown in FIG. 9 a, the impact tip 907 a is securely press fit to the forward end 903 a to form the bond, while in the embodiment shown in FIG. 9 b, the impact tip 907 b is brazed to the forward end 903 b to form the bond. In both embodiments, a body 906 a, 906 b comprising a cavity 926 a, 926 b passing completely there through is detachably and nonrotatably fastened to the forward end 903 a, 903 b. The impact tip 907 a, 907 b may extend through the cavity 926 a, 926 b for engagement with a formation.

FIGS. 10, 11 and 12 disclose embodiments of various types of formation degradation machines each comprising a plurality of pick tools disposed thereon. The formation degradation machines shown may be driven such that the pick tools engage and degrade a degradable surface. For example, FIG. 10 discloses an embodiment of a formation degradation machine in the form of a trencher 1000. The trencher 1000 may comprise a rotatable wheel 1002 comprising a plurality of pick tools 1020 disposed around an exterior thereof. The pick tools 1020 may engage and degrade a degradable surface 1001 to form a trench when the rotatable wheel 1002 is driven.

FIG. 11 also discloses an embodiment of a formation degradation machine in the form of a trencher 1100. The trencher 1100 may comprise a continuous chain 1102 comprising a plurality of pick tools 1120. The pick tools 1120 may engage and degrade a degradable surface 1101 to form a trench when the continuous chain 1102 is passed over an exterior of a boom 1132.

FIG. 12 discloses an embodiment of a formation degradation machine in the form of a drill bit 1200. A plurality of pick tools 1220 may be disposed on the drill bit 1200 that may engage and degrade a degradable surface (not shown) when the drill bit 1200 is rotated.

Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention. 

What is claimed is:
 1. A pick tool assembly, comprising: a shank comprising a forward end and a rearward end; the rearward end formed for retention in a bore of a block attached to a driving mechanism; the forward end comprising a body detachably and nonrotatably fastened thereto; and an impact tip bonded opposite the rearward end.
 2. The pick tool assembly of claim 1, wherein the impact tip is bonded to the forward end.
 3. The pick tool assembly of claim 2, wherein the forward end is disposed within a cavity passing completely through the body.
 4. The pick tool assembly of claim 1, wherein the impact tip is bonded to the body.
 5. The pick tool assembly of claim 4, wherein the forward end is disposed within a socket of the body.
 6. The pick tool assembly of claim 5, wherein the body comprises a radial flange disposed adjacent the socket that transfers forces to an outer shelf disposed around an exterior of the forward end.
 7. The pick tool assembly of claim 5, wherein the forward end is press fit within the socket of the body.
 8. The pick tool assembly of claim 7, wherein the forward end is hollow to aid in the press fit.
 9. The pick tool assembly of claim 7, wherein the forward end is slotted to aid in the press fit.
 10. The pick tool assembly of claim 7, wherein the forward end is tapered to aid in the press fit.
 11. The pick tool assembly of claim 5, wherein the forward end comprises a compliant ring disposed thereon to aid in retention within the socket.
 12. The pick tool assembly of claim 5, wherein the forward end comprises a pin insert to aid in retention within the socket.
 13. The pick tool assembly of claim 1, wherein the impact tip is brazed to the body.
 14. The pick tool assembly of claim 1, wherein the shank is nonrotatably retained in the bore of the block.
 15. The pick tool assembly of claim 1, wherein the driving mechanism comprises a drum, wheel, chain, or bit.
 16. The pick tool assembly of claim 1, wherein the impact tip is disposed within a recess of the body.
 17. The pick tool assembly of claim 1, wherein the body comprises at least one detachment groove disposed adjacent the forward end.
 18. The pick tool assembly of claim 1, wherein the forward end comprises at least one detachment groove disposed adjacent the block. 